Klein Mantra Engine/Engine mount

Bobzilla

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So, I had an idea for a project using URT full-suspension bikes as a platform for a motorized bike. The main advantage is that if the engine is mounted to the unified rear triangle (URT), the bike will not have any chain tension issues and the added weight will not cause much sag on the suspension. Also, many of these frames have rear disc brake tabs which is nice.

Many people, including myself, use these bikes (Klein Mantra, Schwinn sweetspot, ibis Szasbo) for single speeding due to their ability to be run with no tensioner.

I think the best candidate for this would be a Klein mantra, as there is a lot of free space below the main frame tube. Just spitballing, I think one bracket mounted around the top of the engine to the top of the swingarm, just below the main busing, would be good and the bottom can be supported by a bracket fabricated to use the bottom bracket.

The question I have is what engine/engine mounting setup would work on a bike like this?

I've included some images outlining what I'm thinking. I do not own a Klein frame so I don't have access to specific dimensions.
 

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I personally think your idea may work best with something electric. Using gas would require a very small engine (±25cc) and reduction transmission system. Even with wide cranks; other clearance issues due to suspension travel is going to be very minimal if any at all.
 
So, I had an idea for a project using URT full-suspension bikes as a platform for a motorized bike. The main advantage is that if the engine is mounted to the unified rear triangle (URT), the bike will not have any chain tension issues and the added weight will not cause much sag on the suspension. Also, many of these frames have rear disc brake tabs which is nice.

Many people, including myself, use these bikes (Klein Mantra, Schwinn sweetspot, ibis Szasbo) for single speeding due to their ability to be run with no tensioner.

I think the best candidate for this would be a Klein mantra, as there is a lot of free space below the main frame tube. Just spitballing, I think one bracket mounted around the top of the engine to the top of the swingarm, just below the main busing, would be good and the bottom can be supported by a bracket fabricated to use the bottom bracket.

The question I have is what engine/engine mounting setup would work on a bike like this?

I've included some images outlining what I'm thinking. I do not own a Klein frame so I don't have access to specific dimensions.
It is going to take quite a bit of engineering like they did with the Motoped
 

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Something like this with a pumper carb would work. You would need to use the BB for a jack shaft and to stabilize the mount on your alloy frame.
 
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I personally think your idea may work best with something electric. Using gas would require a very small engine (±25cc) and reduction transmission system. Even with wide cranks; other clearance issues due to suspension travel is going to be very minimal if any at all.
Yeah I’d really like to get my hands on one of these frames so I can dimension everything out. I might try to make a rough draft in solidworks if I get to renew my student license.

I was also thinking maybe smaller rims with fat tires could increase clearance and run it more like a BMX. I’ve done this to a normal bike and it was a ton of fun
 
What about electric. Battery on the top tube and mid drive like bbshd or toseven dm?
I’m not very electrically inclined and I think ICE is cooler, but electric is def the way to go from a practical standpoint.

I just was looking at some frames on Facebook and got me thinking what would be some interesting platforms for motorized bikes
 
Yeah I’d really like to get my hands on one of these frames so I can dimension everything out. I might try to make a rough draft in solidworks if I get to renew my student license.

I was also thinking maybe smaller rims with fat tires could increase clearance and run it more like a BMX. I’ve done this to a normal bike and it was a ton of fun
If you can weld, a lot of customation options becomes available to you.
 
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